Are the maps and contents in the Nexuiz 35 Map Pack under the GPL license? How about those on nexuiz ninjas?

Are you talking about the Q3 map pack?

If you are, then no, I don't think many (if any at all) are under the GPL. That's why they're distributed as a separate package. However, I believe they all have provisions that allow them to be redistributed as long as credit is given to the original author (which it is).

Yeah the Q3 Mappack is custom maps for quake 3 that also happen to work in Nexuiz because they use no q3 textures at all and are allowed to be distributed. AFAIK they are NOT GPL though..

The maps on Nexuiz Ninjas are custom maps for Nexuiz and quite a few/most of them are GPL.. You will have to check the pk3 file for a comment though to make sure

Btw, is the mappack being updated in any way? Like MapInfo and stuff?
I remember some issues with 2.4 compatibility...

No basicly that stuff was fixed by code.. but having someone do .mapinfo files for all the maps would be nice!